Workshop rationale and aim

Most recently, fine particulate pollution gave rise to debate in
numerous European countries as concentration limits were overstepped
more frequently and more clearly than in the past. Urban areas were
especially affected. Industry, traffic, agriculture and residential
heating proof mainly responsible for high fine particulate emission
levels. In Austria for instance, within the residential heating sector
small-scale biomass combustion plants are responsible for about 88% of
the PM₁₀ emissions, most of them (about 86%) are
poorly controlled old
biomass combustion systems.

Compared to oil or natural gas, biomass contains a considerable amount
of ash. This inevitably leads to fly ash emissions during combustion. In
medium and large-scale biomass combustion systems fly ash emissions are
typically efficiently precipitated by appropriate filters (ESP or
baghouse filters). Small-scale (residential) biomass combustion plants
however, are not equipped with filters due to economic reasons and the
immature status of the technology. Fly ash emissions of complete biomass
combustion, which is usually achieved by modern and automatically
controlled small-scale biomass combustion plants, consist mainly of
inorganic aerosols and are related to the PM1 fraction (particulate
matter with a particle size smaller 1.0 µm). Carbonaceous aerosols are a
product of incomplete combustion, which is often the case in poorly
controlled old biomass combustion systems or natural draught systems
(like chimney stoves or tiled stoves), and consist of elementary carbon
(soot) or condensed hydrocarbon compounds (organic aerosols). Moreover,
old residential heating systems emit considerably higher PM1 emissions
than modern small-scale biomass combustion systems. The formation of
carbonaceous aerosols can be notably reduced by technical measures
concerning combustion and process control technology (primary measures).
The formation of inorganic aerosols however cannot be significantly
prevented in the same way but needs new “Low-Dust combustion”
technologies or requires secondary measures such as dust precipitators.

Fine particulate matter is the thoracic fraction out of total
particulate matter, i.e. the fraction that can pass the larynx and reach
the lung. There is strong epidemiologic indication that particulate
matter in air has serious adverse health effects, but there are also
indications that there exist considerable differences regarding the
toxicological effects between inorganic aerosols and
carbonaceous
aerosols, which is of great
relevance for the environmental evaluation of different small-scale
biomass combustion technologies.

The workshop accommodated the aforementioned issues by its three key
topics “Low-Dust combustion technologies”, “Small-scale precipitators”
and “Health effects” and thus gave a comprehensive overview of
ongoing developments and recent findings.The
event took place as a parallel session within the 3^rd
Central European Biomass Conference 2011 in Graz, Austria.

SUMMARY OF
THE PRESENTATIONS

Presentations

Organised in cooperation with IEA Bioenergy, TU Graz, Bioenergy 2020+